Means for providing drag in aircraft



March 28, T KNOX [Ti-AL MEANS FOR PROVIDING DRAG IN AIRCRAFT 2Sheets-Sheet 1 Filed July 29, 1942 NTORS M5 Iv m Em R v Z 0 N w a A KM mmm March 28, 1944. T. KNOX ETAL MEANS FOR PROVIDING DRAG IN AIRCRAFTFiled July 29, 1942 2 Sheets-Sheet-Z INVENTORS ama /(/;a, r 4 10 22' M14 ryn ATTORNEYS Fatented it lure 28, i944 li t i i did lcrwf i I W? isS EAQ as dri l HQE MEANS FOR PRQVKDKNG DRAG llN AHRQRAFT Thomas Knox,Bristol, and William H. Stieglita,

Morrisville, 19s., assignors, by mesne assignments, to ReconstructionFinance Corporation Application .luly 29, 194 .2, Serial No. iSZfiWi lillaim. (Cl. 2441-42) This invention relates to aircraft andparticularly to auxiliary flaps adapted to be adjusted in.

.ight to afford additional drag, and thereby to decrease the speed ofthe aircraft in a dive or to permit rapid deceleration in level flight.

in modern aircraft, it is usual to employ rnov acle slaps on thetrailing edge of the wings, in board of the ailerons. These landingflaps are set by the operator at the desired angle when the aircraft isabout to land, to assist in bring ing it into proper position forlanding and to provide additional lift and drag in the landingoperation. The landing flaps when set in angular relation to the wingsalfect the trim of the aircraft. Such flaps when partially deflected maybe used to reduce the take-off run of heavily loaded aircraft byproviding a substantial increase in lift with a relatively smallincrease in drag.

When an aircraft is executing a diving maneuver as in dive bombing, itis frequently desirable to reduce velocity without aiiecting trim.Likewise i1" a'fighting aircraft approaches another while traveling toorapidly, prompt reduction of speed without afiecting alignment of gunsights is essential. The desired braking efiect cannot be accomplishedby operation of the landing iiaps.

It is the object of the present invention to rovide auxiliary andindependently operable naps supported on the landing flaps and adaptedto be moved simultaneously to angular positions with respect to thelanding flaps to afford the desired drag or braking efiect withoutaffecting the trim of the aircraft.

Another object of the invention is the provision of means afiordingadditional drag whichperforms the desired function without setting upundesirable eddy currents and thereby causing erratic operation.

Another object of the invention is the provision of means affording thedesired drag which, when not in use, are so disposed as not to introduceunnecessary and detrimental drag in the operation of the aircraft.

Other objects and advantages of the invention will be apparent as it isbetter understoodoloy reference to the following specification andaccompanying drawings, in which Fig. l is a transverse section through awing and flap with the auxiliary flaps mounted there Fig. 2 is anenlarged sectional view il1ustrat ing one of the auxiliary flaps inrelation to the main flap;

3 is an enlarged plan view of a section of the main and one of theauxiliary flaps; and

Fig. 4 is a diagrammatic sectional view illushating the operating meansfor the auxiliary naps.

In describing the invention, the auxiliary flaps are considered asaccessories to landing flaps which are pivotally secured to the wings ofthe plane. Referring to the drawings, 5 indicates a wing of any suitableconstruction having a landing flap l5 pivotally connected at thetrailing edge thereof. The details of the landing flap and itsconnection with the wing structore form no part of the presentinvention, such structures being common in the art.

The landing flap is provided with recesses l on the opposite facesthereof, and the auxiliary flaps 8 are pivoted at 9 and normally rest inthe recesses so as to afford a streamlined outer surface on the landingflap. The auxiliary flaps 8 are designed to be moved to the positionindicated in full lines in Fig. l by the operator or" the plane when itis necessary or desirable to retard the speed of the plane.

To avoid the production of undesirable eddy currents, the auxiliaryflaps i may be provided with a plurality of relatively large openingsill, distributed over the entire suriace of each of the auxiliary flaps.Where such openings are provided, they would normally interrupt thesurface when the auxiliary flaps are in closed position, that is to saydisposed in the recesses in the landing flap. To avoid this difiiculty,the surface of the landing flap is provided with a plurality of bossesii arranged to register with the openings l9 when the auxiliary flapsare in closed position. This affords a smooth streamlinedsuriace,avoiding the introduction of undesirable drag when the auxiliaryflaps are not in use.

To permit the performance of the desired function, the auxiliary flaps tare moved simultaneously to operative position in angular relation tothe landing flap. This control may be effected in any practicablemanner. One practicable adaptation of mechanism permitting simultaneousoperation of the flaps is indicated diagrammatically in Fig. 4 in whichthe auxiliary flaps ll, pivoted at 9 in the structure of the landingflap 5, are provided with. arms l2 inwardly directed and connected bylinks it to a piston rod l i carrying a piston to in a cylinder it.Fluid under pressure may be supplied under control of a suitable valve(not shop? 3 to the cylinder it through inlets H on oppos e sides of thepiston 5 to actuate the latter in either direction. Such movement willactuate the auxiliary flaps 8 to the open or closed position as may bedesired, and hold them rigidly in the selected position. No attempt ismade herein to illustrate or describe the details of the hydraulicactuating mechanism which is commonly employed for similar purposes inthe art.

The apparatus as described afiords a simple and effective means foraccomplishing the desired purpose. When the aircraft is flying undernormal conditions, the auxiliary flaps will be closed and inelfective.When braking effect is required, the operator may, by a simple movement,adjust the auxiliary flaps to their operative position at which theybecome eflective for the purpose of the invention. No further attentionis required, as the auxiliary flaps perform their function -withoutadjustment. It is, of course, essential that the auxiliary flaps beoperated in pairs in order to afford the necessary balance and thusavoid diverting the plane from its intended path under control of theoperator.

- ously from the recesses to positions projecting angularly withrelation to the landing flap.

THOMAS KNOX. WILLIAM I. STIEGLITZ.

